1. Field of the Invention
This invention relates to squeezing pipe and to rerounding the squeezed pipe and, more particularly, to a single apparatus capable of both squeezing off pipe and then rerounding the squeezedoff pipe.
2. Description of the Prior Art
U.S. Pat. No. 134,349 discloses apparatus for forming rings around a mandrel. The die for forming the rings includes two semicircular portions which are forced together around the mandrel, and the ring to be formed is pressed by and between the dies and around the mandrel to form the ring. While this patent does not relate to the present apparatus, it discloses apparatus for forming a metal ring around a cylindrical mandrel, and the forming dies are each semicircular in configuration.
U.S. Pat. No. 467,657 discloses a hydraulic system for forming metal rings or bands around artillery shells. The apparatus comprises four hydraulic cylinders spaced ninety degrees apart and each connected to a die. Each die comprises a quarter of a circle, and the four dies together form a complete circle. The cylinders and dies are spaced ninety degrees apart from each other and are located on a common center. As the cylinders and dies move inwardly, the metal ring is formed around the centered artillery shell.
U.S. Pat. No. 694,177 discloses apparatus for straightening dents in cans by having a fixed concave die surface and a movable die member which has a mating convex surface. Cans to be straightened are placed on a concave die, and the convex die is then moved against the can to press the dent out of the can by forcing the dented metal between the convex and concave die portions.
U.S. Pat. No. 889,728 discloses apparatus for reducing the diameter of the ends of boiler tubes. The apparatus includes two die portions, a lower fixed die and an upper, movable die, each of which is concavely semicircular in configuration. The upper semicircular die is pressed downwardly against the fixed semicircular die. The end of the tube to be diametrically reduced is disposed on the bottom die, and when the upper die is forced downwardly, the reduction in diameter occurs.
U.S. Pat. No. 1,879,078 discloses pipe forming apparatus in which a movable die is moved downwardly against a fixed die, and a flat metal blank is placed on the bottom die. The movable die includes two different portions, so that two different forming operations are accomplished by the movable die. After the tubular pipe is partially formed by the two dies, a pair of semicircular dies is then used to complete the rounding of the preformed tube. The semicircular dies include a movable portion and a fixed portion, with the preformed blank placed in the fixed portion.
U.S. Pat. No. 2,202,125 discloses pipe press apparatus for joining two pipes together. The pipes are of different diameters, and are pressed together by two semicircular dies. Explosive forces are used to move the upper, movable die downwardly against the lower, fixed die.
U.S. Pat. No. 2,903,929 discloses apparatus for swaging ferrules in which four die elements are used. The four elements are all movable and each comprise a quarter of a circle. The die elements utilize a combination of pivoting forces to bring the four portions together.
U.S. Pat. No. 4,445,357 discloses apparatus for forming pipe from a blank steel sheet. A plurality of hydraulic presses is used to form the pipe in two operations. Hydraulic presses operate in both an X and a Y direction, with the forming operation taking place in two steps, the first being actuation of the horizontally opposed X-direction presses, and the second operation being the actuation of the vertically moving Y-direction presses. The actuation of the X-direction presses forms a flat blank into a generally elongated U-configuration. Then, the actuation of the vertically oriented Y-direction presses completes the rounding of the U-shaped blank into a pipe.
According to the prior art, it is well known and understood that pipe elements or blanks may be rounded by the application of force to semicircular dies. However, what is not shown in the prior art is that a single machine may be utilized for squeezing off a pipe and then rerounding the pipe. It will be noted that the teachings of the prior art patents discussed above involve the rounding of pipe either from a blank or in reducing the diameter of an existing circular element. However, none of the patents disclose the rerounding of a deformed pipe, as with pipe that has been deliberately deformed or squeezed off.
The apparatus of the present invention is capable of both squeezing off pipe in a single operation, and then of rerounding the squeezed off pipe in a single operation. Thus, two independent operations are performed by the same apparatus, namely squeezing off pipe and then rerounding the squeezed off pipe.